(1) Field of the Invention
This invention relates generally to the field of breast cancer pathogenesis and, more particularly, to a cDNA sequence and encoded mammary-specific protein for use in detecting and treating breast cancer.
(2) Description of the Related Art
Breast cancer is one of the most common and potentially lethal of cancers. Although early diagnosis and treatment can reduce morbidity and mortality related to the disease, the positive predictive value of mammography has been estimated to be only about 25% (Hall et al., N Engl J Med 327: 319-328, 1992 which is incorporated by reference). It would, therefore, be desirable to have a means for detecting the cancer earlier than the cancer can be detected using mammography and a genetic or biochemical marker might be able to provide such means to complement and increase the predictive value of mammography. (Hayes, Hematol Oncol Clin N Am 8: 485, 1994 which is incorporated by reference).
The development of breast cancer is accompanied by a number of genetic changes (For review see Porter-Jordan, Hematol Oncol Clin N Am 8: 73, 1994 which is incorporated by reference). Such changes include gross chromosomal alterations and loss of genetic markers (Devilee et al, Biochim Biophys Acta 1198: 113, 1994; Callahan et al, J Cell Biochem Suppl 17: 167, 1993 which are incorporated by reference). The progression of breast neoplasia has also been shown to result in qualitative and quantitative changes in expression of previously identified genes that encode growth factors and their receptors (Zajchowski et al., Cancer Res 48: 7041, 1988 which is incorporated by reference), structural proteins (Trask et al., Proc Natl Acad Sci 87: 2319, 1990 which is incorporated by reference), second messenger proteins (Ohuchi et al., Cancer Res 26: 2511, 1986 which is incorporated by reference), and transcription factors (Harris, Adv Cancer Res 59: 69: 1992 which is incorporated by reference). These changes in gene expression could potentially form the basis for developing a breast cancer marker, although the precise role of these gene changes in the pathogenesis of breast carcinoma in patient biopsy samples is not well understood.
In addition to providing a genetic or biochemical marker for breast cancer for early detection of the disease, it would also be desirable to have a tumor marker that might provide an estimation of prognosis, a means for selection and evaluation of therapy and a means for the targeting of therapy. Although a number of tissue markers have been identified, none are sufficiently sensitive or tumor specific to be ideally suited for diagnosis or for screening the general population. (Id.). Thus, there remains a continuing need for a breast cancer marker such as a gene along with its expressed protein that can be used to specifically and selectively identify the appearance and pathogenic development of breast cancer in a patient.
Using a modified differential display polymerase chain reaction technique to isolate differentially expressed sequence tags from mammary carcinoma, several sequence fragments were isolated that were uniquely expressed in neoplastic mammary epithelial tissue as compared to normal tissue controls (Watson and Fleming, Cancer Res 54: 4598-4602, 1994 which is incorporated by reference). The discovery of one of these sequence tags identified as DEST002 has led to the discovery and isolation of the novel full length cDNA and encoded protein now referenced as mammaglobin. The cDNA and protein are both new.